Method of forming plastic bag with integral tie

ABSTRACT

A plastic film web is perforated and sealed at the open end of a bag to provide an integral tear strip portion of the bag material which can later be either wholly or partially detached for use as a closure tie.

United States Patent [191 White Dec. 18, 1973 PLASTIC BAG WITH INTEGRALTIE AND METHOD OF FORMING SAME [75] Inventor: Daniel A. White, GreenBay, Wis.

[73] Assignee: FMC Corporation, San Jose, Calif.

[22] Filed: Feb. 16, 1972 [21] Appl. No.: 226,710

[52] US. Cl 93/35 VL, 93/1 TS, 93/35 DS, 93/33 H [51] Int. Cl B31b 1/90,B3lb 49/04 [58] Field of Search 93/35 R, 35 DS, 35 VL, 93/1 TS, 33 H, 35H, 58 P [56] References Cited UNITED STATES PATENTS Peterson 93/35 R3,567,074 3/1971 Brown 93/1 TS 3,411,419 11/1968 Becker et al.... 93/19X 3,283,672 11/1966 Mueller 93/1 TS X 3,579,397 5/1971 Schwarzkopf..93/1 TS 2,643,049 6/1953 Barelt 93/35 R X 3,568,576 3/1971 Lehmacher eta1 93/33 H Primary Examiner-Andrew R. Julhasz Assistant Examiner.lamesF. Coan Attorney-F. W. Anderson et a1.

[ 5 7 ABSTRACT A plastic film web is perforated and sealed at the openend of a bag to provide an integrall tear strip portion of the bagmaterial which can later be either wholly or partially detached for useas a closure tie.

4 Claims, 15 Drawing; Figures PATENTED DEC! 81375 SHEU 1 [IF 3 PLASTICBAG WITH INTEGRAL TIE AND METHOD OF FORMING SAME BACKGROUND OF THEINVENTION The field of the present invention concerns plastic film bags.Relatively recent convenience products for residential and other usersare a wide variety of inexpensive plastic film bags intended for limitedor onetime use. Among these, at present, are large trash bags or trashcan liners which are usually packaged with loose tying devices such aspaper or plastic covered wire ties for closing the throat of the bagafter filling. The ties must be separately manufactured, handled andcounted, and can easily be dislodged from the packaged bags and lost,and for these reasons are less than satisfactory both to themanufacturer and the consumer. Moreover, the ties increase the cost tothe consumer since they are separately produced and handled. A furtherdisadvantage in separate ties is that even after a tie has been placedon a bag, it can easily become detached and allow the bag to open orspill.

SUMMARY OF THE INVENTION By perforating the margin of a bag around theopen end during its production, a separable tear strip formed of the bagmaterial is later readily freed for use as a closure tie. Thus the tieand the bag are formed, handled and packed as a unit to eliminate theinherent disadvantages of separate bags and closure ties, and can beproduced at rates as high as are now attained for ordinary bagsrequiring separate ties. The tear strip tie can be made either entirelyor partially separable, and can be either single ply, multi-ply, or areinforced form of either.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side elevationof a bag making machine adapted to carry out the bag forming method andto produce the bag article of the present invention.

FIG. 2 is an enlarged schematic elevation including a sealing andperforating mechanism at the inlet end of the bag machine shown inFIG. 1. i I

FIG. 3 is an enlarged schematic elevation of a selectively operableperforating mechanismshown in FIG. 1.

FIG. 4 is a schematic perspective of the FIG. 2 perforating mechanism.

FIG. 5 is a schematic perspective of a web sealing and severing stationof the bag machine.

FIG. 6 is a schematic isometric of one embodiment of a completed bag.

FIG. 7 is a schematic perspective of the FIG. 6 bag after filling andtying.

FIGS. 8-15 are schematic perspectives of further embodiments of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a known typeof bag making machine 20, which. in the present case is arranged to heatseal and sever a prefolded film web W supplied from a roll R. The web Wis supplied longitudinally folded so that one edge is slightly spacedfrom the other edge, in the form known, due to this type of fold, asJ-stock. When the foldedweb is eventually sealed and severed across itswidth, two adjacent sealing and severing operations produce one bagknown as a side-weld bag because the sealed and severed portions extendalong the side margins of the completed bag.

Driven draw rolls at 22 continuously pull the web W from the roll R andpast a folding station 24 at which one narrow edge portion of the web isdoubled to make two plies, or in certain instances, several plies.Beyond the draw rolls, the web is trained around an anvil roll 26 at aselectively operable sealing and perforating station 28 where the doubleplies are sealed together and the adjacent single ply is perforated sothat the doubled edge portion can later be torn from the remaining webin a completed bag.

Because the web feed downstream of the perforating station 28 isintermittent, the web is trained through a conventional dancer rollassembly 30 which operates to automatically accumulate and pay out theweb according to the web requirements downstream of the dancer rollassembly. The next station is a selectively operable intermittentperforating station 32 which is used only when the perforating mechanismof the sealing and perforating station 28 is inactive.

The intermittent perforating station 32 produces in terrupted bagperforations, whereas the station 28 produces continuous perforations.As previously indicated, continuous perforations provide a removabletear strip, while the interrupted perforations retain the tear stripattached to the body of the bag. In some instances where the tear stripincludes more than one ply, selected portions of the tear strip can beconsolidated by a spot-sealing operation at a sealing station 34,following which the web passes through the intermittent feed rolls at36, and a sealing and severing station at 38 where the side margins ofthe bag are simultaneously sealed and severed from the web. A conveyingsection at 40 then transfers the finished bags onto a stacking table 42where they are assembled into stacks and are subsequently removed forpackaging or other handling. Those stations of the bag machine 20 whichdiffer from a conventional bag machine are stations 24, 28, 32 and 34,as will presently be described. 1

With more specific reference to both an exemplary form of the bag and tothe apparatus for producing the bag, reference is made to FIGS. 4 7. Theprefolded web W adjacent the draw rolls 122 includes a lower panel 44and a narrower upper panel 46. At the folding station 24 the exposededge 48 of the lower panel 46 is guided through a stationary foldingshoe 50 (FIG. 2) which functions to fold back a narrow hem or skirt 52which ultimately becomes one edge of the open end of a bag B, as clearlyshown in FIG. 6. The folding shoe 50 is actually the hemming attachmentof a conventional household sewing machine, and functions in the usualmanner, whereby according to the width of the margin of material runthrough the attachment, either a single fold of U-shape section will beformed, or a double fold having the edge of the material disposed withinthe confines of a U-shaped fold.

Again referring to FIG. 4, the sltirt 52 on the folded edge of the webpasses around the anvil roll 26 and under a cooperating perforatingwheel 54 to form a linear series of spaced perforations at 56 betweenthe previously identified edge 48 of the web panel 46, and an edge 58 ofthe web panel 44, and through both the skirt 52 and the web panel 46. Atthe same time the perforations are made, an electrically energizedsealing bar 60 continuously heat-seals the skirt 52 to the web panel 46.An air cylinder 62 carries the sealing bar 60 so that the sealing barcan be removed from the web when the machine is idle, or when a laterdescribed optional procedure is used and no longitudinal sealingoperation is required. Thus folded, heat-sealed, and made separable fromthe remainder of the web, the skirt 52 now forms a removable tear stripTS when the web is later transversely sealed and severed.

When producing the bag B shown in FIGS. 6 and 7, the only remainingoperation is the sealing and severing of the web W (FIG. by aconventional heated sealing bar 64 which is actuated each time the feedrolls 36 (FIG. 1) have advanced one bag length of web, and the web isstatic. None of the described folding, sealing and perforatingoperations interrupt progress of the web, because each is a continuousoperation. For this reason, the production rates of the bag machine aresubstantially as high as have formerly been attained. Moreover, the tearstrip TS is an integral part of the bag having the same handlingcharacteristics as the body of the bag, and the bags B can therefore behandled in stacking and packing operations with the same procedurespresently in use. In contrast to present bags, however, the bag B nowhas a readily separable closure the tear strip TS which cannot beaccidentally dislodged, lost or misplaced, and which is ready forimmediate use when needed.

, FIGS. 8-15 disclose some of the numerous possible other embodiments ofthe bag and bag forming method of the present invention, the structuralmeans for effecting the same being the same elements already described,plus a spot-sealer 66 (FIG. 1) at the sealing station 34, and askip-perforator 68 (FIG. 3), at the perforating station 32, which isused in lieu of the mechanism at the perforating station 28.

FIG. 8 illustrates a bag B1 which is similar to the bag B but has asingle ply, only, in its tear strip TS, thus being formed wihtout use ofthe folding shoe 50, and being a suitable construction for a light dutybag, or for a bag of one of the stronger film materials. It will beunderstood that in FIG. 8, as well as in FIGS. 9-15, the side margins ofthe bag are shown open in order to clearly illustrate the plies, andthat in actuality these margins are sealed together by a sealing bar 64at station 38 as each bag is severed from the upstream web portion.

FIG. 9 depicts a bag construction for a bag B2 in which the tear stripTS comprises a once folded web portion, as in the bag B, but wherein thearcuate sealing bar 60 (FIG. 4) is retracted by the air cylinder 62 toeliminate the longitudinal seal through the tear strip. In place of thattype of seal, the spot-sealer 66 produces two spaced area seals,indicated by shaded areas at 70, which secure the two plies together atthe ends of the tear strip and thus preserve the dual ply construction.Since the actual length of a tear strip in a trash can liner might betwo feet or more, it is apparent that the central portion of the tearstrip can easily be opened flat, if desired, so as to provide a widewrap around the throat of the ba g. bag.

The FIG. 10 bag B3 is comparable to the bag B, with an additionalfolding step which may be accomplished by repositioning the folding shoe50. As previously mentioned the width of material run through thefolding shoe determines the type of fold. Thus, when the margin is about94 inch, a 1% inch fold is made, plus a V4 inch return fold. Thisproduces three plies through part of the folded margin. It might also bepossible to use a different folding shoe to produce a similar but fourply fold in the form of a flattened helix. In either event, the arcuatesealing shoe 60 is used to interconnect all plies with a longitudinalseal through the tear strip TS, and the thus produced tear stripprovides a stronger than usual tie for the bag.

Bags B4-B6 (FIGS. l113) all have single ply tear strips TS, and areformed by inactivating or removing the folding shoe 50 (FIG. 4), theperforating wheel 54, the sealing shoe 60, and the spot sealer 66 (FIG.1), and by use of the skip-perforator 68 (FIGS. 1-3). As best shown inFIG. 3, the skip-perforator includes rollers 72, 74 for guiding the webW around an anvil roll 76. A perforator wheel 78 is carried by a pivotarm 80 for selective engagement with the web by means of a powercylinder 82. Automatic, programmed operation of the perforator wheel forproducing a preselected pattern of perforations may be effected indifferent ways, a preferred way (not shown) being a camoperated valvetimed to the operation of the bag machine 20 for energizing anddeenergizing the power cylinder 82.

A common feature of the bags 84-36 is that the perforations 56 of thetear strip TS in each case is interrupted so that the tear strip has amajor portion separable from the bag, but remains connected to the bagat one or more points. By this means, the tear strip retains its closureutility, as intended, but cannot slip off the bag when it is wrapped andtied around the throat of the bag. Thus, in FIG. 11 the bag B4 isprovided with a tear strip TS having opposed free end portions v84centrally interrupted and thereby connected to the bag panel 46. In FIG.12 the bag B5 has an attached tear strip TS with only one free end 86,whereas the tear strip of the bag B6 (FIG. 13) has no free ends.

The bag B7 (FIG. 14) is provided with a two ply tear strip TS which hasno free ends and is produced by use of the folding shoe 50 (FIG. 4) toform the double ply, and by use of the spot-sealer 66 (FIG. 1) to bondthe two plies together with area seals at 88. By means of area seals(FIG. 15) and non-interrupted perforations 56, the tear strip TS of thebag B8 is especially adapted for initial use as a handle, and forpossible eventual use as a closure tie. While the perforations 56 (whichextend only through the bag panel 46) may be interrupted to stop shortof the side margins of the bag, an advantage of the FIG. 15 constructionis that it eliminates the more elaborate mechanism for skipperforating.

From the preceding description, it is believed evident that thedisclosed bags and bag forming method represent a marked improvementover bags of the separate closure-tie type, in that the ties areintegral with the bags, cannot be lost, andare capable of beingsimultaneously produced at less cost than separate closure ties.Further, the conventional handling operations used for ordinary bags arenot affected by the integral closure ties, and there are no separatehandling steps required for the ties.

Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodification and variation may be made without departing from what isregarded to be the subject matter of the invention.

I claim:

1. A bag forming method comprising the steps of moving a longitudinallyfolded web along a predetermined path, longitudinally perforating theentire bag near the upper longitudinal edge thereof, and transverselysevering and sealing said web at spaced intervals to form one bag withtwo successive severing and sealing operations, the marginal portion ofthe perforated ply providing a tear strip at least partially separablefrom the thus formed bag for use as a closure tie, said perforating stepproducing interrupted perforations for leaving a part of said tear stripinseparable from the bag.

2. A bag forming method comprising the steps of moving a longitudinallyfolded web along a predetermined path, longitudinally perforating theentire bag near the upper longitudinal edge thereof, and transverselysevering and sealing said web at spaced intervals to form one bag withtwo successive severing and sealing operations, the marginal portion ofthe perforated ply providing a tear strip at least partially separablefrom the thus formed bag for use as a closure tie, folding the marginaledge portion of the ply which ultimately forms said tear strip to make adouble ply, and sealing said double plies together to form a doublestrength tear strip in the completed bag.

3. The method of claim 2, wherein said sealing step longitudinally sealssaid tear strip plies.

4. A bag forming method comprising the steps of moving a longitudinallyfolded web of J-stock along a predetermined path, folding the marginaledge portion of the wider ply which ultimately forms said tear strip toform a double ply, sealing each end portion of said double pliestogether, longitudinally perforating the wider ply near the upperlongitudinal edge of the narrower ply to form a tear strip, andtransversely severing and sealing said web at spaced intervals to formone bag with two successive severing and sealing operations, themarginal portion of the perforated wider ply providing a doublethickness tear strip at least partially separable from the thus formedbag for use as a closure are w =r

1. A bag forming method comprising the steps of moving a longitudinallyfolded web along a predetermined path, longitudinally perforating theentire bag near the upper longitudinal edge thereof, and transverselysevering and sealing said web at spaced intervals to form one bag withtwo successive severing and sealing operations, the marginal portion ofthe perforated ply providing a tear strip at least partially separablefrom the thus formed bag for use as a closure tie, said perforating stepproducing interrupted perforations for leaving a part of said tear stripinseparable from the bag.
 2. A bag forming method comprising the stepsof moving a longitudinally folded web along a predetermined path,longitudinally perforating the entire bag near the upper longitudinaledge thereof, and transversely severing and sealing said web at spacedintervals to form one bag with two successive severing and sealingoperations, the marginal portion of the perforated ply providing a tearstrip at least partially separable from the thus formed bag for use as aclosure tie, folding the marginal edge portion of the ply whichultimately forms said tear strip to make a double ply, and sealing saiddouble plies together to form a double strength tear strip in thecompleted bag.
 3. The method of claim 2, wherein said sealing steplongitudinally seals said tear strip plies.
 4. A bag forming methodcomprising the steps of moving a longitudinally folded web of J-stockalong a predetermined path, folding the marginal edge portion of thewider ply which ultimately forms said tear strip to form a double ply,Sealing each end portion of said double plies together, longitudinallyperforating the wider ply near the upper longitudinal edge of thenarrower ply to form a tear strip, and transversely severing and sealingsaid web at spaced intervals to form one bag with two successivesevering and sealing operations, the marginal portion of the perforatedwider ply providing a double thickness tear strip at least partiallyseparable from the thus formed bag for use as a closure tie.